Microtomes and ultramicrotomes are, as a rule, equipped with at least one knife that serves for the production of thin sections of a sample. Microtomes and/or ultramicrotomes are enclosed in the region of the knife holder and the sample holder, as applicable, by a cooling chamber. The samples can then be produced in thin sections at low temperatures. Before the samples can be sectioned, they are trimmed in suitable fashion.
For sectioning at room temperature, trimming machines that are equipped with a milling cutter are known from the existing art (see Leica EM TRIM brochure). With the trimming machine, the specimen is shaped into the form of a four-sided pyramid. The tip of the pyramid is then milled down. This surface then constitutes the (usually rectangular) precut surface or front surface proceeding from which the thin sections are produced.
If sectioning is performed at low temperature in a cooling chamber, however, it is not possible to use an external trimming device at room temperature. The purpose of the invention is to develop a trimming method for low-temperature applications that can proceed automatically.
With the Leica EM FCS cooling chamber (“Low-Temperature Sectioning System” brochure), trimming takes place in the cooling chamber. The trimming knife is used both to shape the specimen on the sides and also to cut across the front surface of the sample. After a rotation of the sample, the two side surfaces are shaped in turn. The result is to produce a rectangular precut surface, or the front surface. The trimming operation encompasses bringing the trimming knife close, precutting the front surface, laterally displacing the trimming knife, shaping the side surface, displacing the trimming knife to the other side of the sample, shaping the other side surface, rotating the sample 90°, displacing the trimming knife, shaping the side surface, displacing the trimming knife again, and shaping the fourth side surface. The method just described according to the existing art can take up to an hour, and therefore usually takes longer than the actual production of thin sections. The user must set the individual steps on the unit, and is thus “tied” to the unit for sample trimming and cannot perform any other work. Only sectioning of the sample is motorized.